Meningococcal disease (MD) is a serious public health problem, with high morbidity/mortality rates and case-fatality rate of approximately 10-20%. In 2007, the Brazilian National Immunization Program started to provide meningococcal C conjugate vaccine (MenC) for all HIV infected children, although there is no evidence that support this measure. It is neither proven that HIV infected children are in increased risk to MD, nor that MenC would be immunogenic in this population. The main aim of this proposal is to evaluate the immune response to MenC in HIV infected children. The sampling frame for this proposal is the approximately 180 persons enrolled at Instituto de Puericultura e Pediatria Martagao Gesteira, in Rio de Janeiro, Brazil. We will use a cohort design in our research targeting HIV infected children 2-13 years old who are assisted at the at IPPMG. These children during their regular appointment with their health care provider will be counseled to be immunized with MenC, and they will be invited to participate in this study. They will be immunized with 1 dose of the vaccine. Immune response of these children (serum bactericidal assay - SBA titers and Elisa) will be evaluated before the immunization, 30-60 days, and 12-18 months after the immunization. In this proposal we are going to study the short and long term response to the MenC, and comparing short term responders and non-responders to the vaccine, to assess possible factors associated with the response. PUBLIC HEALTH RELEVANCE: Meningococcal disease (MD) is a serious public health problem, with high morbidity/mortality rates. The main aim of this project is to evaluate the immune response of meningococcal C conjugate vaccine in a group of HIV infected children.